Moerkens R.,University of Antwerp |
Gobin B.,Pcfruit |
Peusens G.,Pcfruit |
Helsen H.,Applied Plant Research |
And 4 more authors.
Agricultural and Forest Entomology | Year: 2011
1 Phenological day degree models are often used as warning systems for the emergence of arthropod pests in agricultural crops or the occurrence of natural enemies of the pest species. In the present study, we report on a case study of the European earwig Forficula auricularia L., which is an important natural enemy in pipfruit orchards, and describe how such a day degree model can be used to avoid negative effects of crucial orchard management, such as spray applications and soil tillage. A precise timing of these interventions in relation to the phenology of natural enemies will enhance biocontrol. 2 Earwig population dynamics are characterized by single- and double-brood populations, each with specific biological characteristics. 3 A day degree model capable of predicting the phenology of local earwig populations of both population types was developed. The model was checked for accuracy by comparing the first field observation dates of various life stages with predicted values using temperature data from the nearest weather station. In addition, variation in development time was assessed using field data. 4 The model was able to make predictions on a global scale. Although single- and double-brood populations differ in phenology, the predictions of first appearance dates were similar. Variation in development time showed that single-brood populations were more synchronized. 5 Our phenological model provides an accurate tool for predicting and simulating earwig population dynamics, as well as for enhancing the biocontrol of pests in pipfruit orchards. © 2011 The Authors. Agricultural and Forest Entomology © 2011 The Royal Entomological Society.
Voogt W.,UR Greenhouse Horticulture |
Van Dijk P.,Wijstwater advies |
Douven F.,BICH |
Van Der Maas R.,Applied Plant Research
Acta Horticulturae | Year: 2014
Although the majority of blueberries in The Netherlands are soil grown, interest in soilless culture has increased recently. Modern cultivation with high yield and fruit quality needs maximum control of growth and crop development, which is expected to be achieved with irrigation and nutrient management. At the same time, reduction of nutrient losses is an important issue for all crops. Both aspects are realized more easily in soilless culture systems than in soil. The research discussed here focused on nutrient demand and the development of a specific nutrient solution for blueberry. Valuable information was gained on nutrient demand, from which a standard nutrient solution was developed and fine-tuned. Compared to all other substrate-grown crops, the total nutrient demand by blueberry was low, especially for K. The results did not show any clear shifts in nutrient uptake ratios during the growing season. Uptake of Na and Cl were very limited, suggesting that high-quality irrigation water is needed for profitable soilless production of blueberry.
Van Evert F.K.,Wageningen University |
Samsom J.,Gagelweg 1 |
Polder G.,Wageningen University |
Vijn M.,LaMi |
And 8 more authors.
Journal of Field Robotics | Year: 2011
Broad-leaved dock is a common and troublesome grassland weed with a wide geographic distribution. In conventional farming the weed is normally controlled by using a selective herbicide, but in organic farming manual removal is the best option to control this weed. The objective of our work was to develop a robot that can navigate a pasture, detect broad-leaved dock, and remove any weeds found. A prototype robot was constructed that navigates by following a predefined path using centimeter-precision global positioning system (GPS). Broad-leaved dock is detected using a camera and image processing. Once detected, weeds are destroyed by a cutting device. Tests of aspects of the system showed that path following accuracy is adequate but could be improved through tuning of the controller or adoption of a dynamic vehicle model, that the success rate of weed detection is highest when the grass is short and when the broad-leaved dock plants are in rosette form, and that 75% of weeds removed did not grow back. An on-farm field test of the complete system resulted in detection of 124 weeds of 134 encountered (93%), while a weed removal action was performed eight times without a weed being present. Effective weed control is considered to be achieved when the center of the weeder is positioned within 0.1 m of the taproot of the weed-this occurred in 73% of the cases. We conclude that the robot is an effective instrument to detect and control broad-leaved dock under the conditions encountered on a commercial farm. © 2010 Wiley Periodicals, Inc.
Kapoerchan V.V.,Leiden University |
Spalburg E.,National Institute of Public Health and the Environment |
De Neeling A.J.,National Institute of Public Health and the Environment |
Mars-Groenendijk R.H.,TNO |
And 10 more authors.
Chemistry - A European Journal | Year: 2010
The cyclic decapeptide gramicidin S (GS) was used as a model for the evaluation of four turn mimetics. For this purpose, one of the D-Phe-Pro two-residue turn motifs in the rigid cyclic β-hairp0in structure of GS was replaced with morpholine amino acids (MAA 2-5), differing in stereochemistry and length of the side-chain. The conformational properties of the thus obtained GS analogues (6-9) was assessed by using NMR spectroscopy and X-ray crystallography, and correlated with their biological properties (antimicrobial and hemolytic activity). We show that compound 8, containing the dipeptide isostere trans-MAA 4, has an apparent high structural resemblance with GS and that its antibacterial activity against a panel of Gram positive and -negative bacterial strains is better than the derivatives 6, 7 and 9. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.
De Haan J.,Applied Plant Research |
Sukkel W.,Applied Plant Research |
Stilma E.,Applied Plant Research
Acta Horticulturae | Year: 2010
Current open field vegetable production systems in the Netherlands do not meet market and societal demands. These demands could not be fulfilled by adapting current production systems. Other kinds of production systems are needed and therefore two types of systems are designed by 1) a technological and 2) an agro-ecological vision. The technological vision aims at excluding and predicting external influences with the focus on control. Variants of this vision are production systems with fertigation and mulching with foil and hydroponic systems. Fertigation combined with mulching improves nutrient and water use efficiency and reduces leaching. Hydroponic systems exclude soil effects as well. The agro-ecological vision aims at creating buffers to make systems resilient against negative external influences with the focus on prevention. The general hypothesis is that diversity improves resilience and sustainability. Examples of various forms of diversity are discussed. The difference in paradigm between both visions is a mostly fundamental difference. The question is whether technological and agro-ecological farming systems can fulfill societal demands and in what timeframe systems will be ready for application in practice. Both visions need to be developed further to have a diverse set of production systems ready.
Gunadi N.,Indonesian Vegetable Research Institute |
Everaarts A.P.,Applied Plant Research |
De Putter H.,Applied Plant Research
Acta Horticulturae | Year: 2015
An experiment to determine the effect of stem number per plant and media container on the growth and yield of sweet pepper (Capsicum annuum var. grossum L.) was conducted at the Indonesian Vegetable Research Institute (IVEGRI), Lembang (1250 m a.s.l.), West Java from May 2006 to February 2007. Two factor treatments i.e., 1) number of stems per plant (2, 3 and 4 stems) and 2) media container (Polybag-10 L of media and Slab-16 L of media) were arranged in a randomized complete block design with three replications. Burned rice husk was used as the growing media. The 2 and 3 stems treatments were carried out in two media containers i.e., polybag and slab, while the 4 stems treatment was only in polybag. The stem density was kept at 8.3 stems m-2 for all treatments. The results of the experiment indicated that the sweet pepper plants with 4 stems had a 3 kg m-2 lower yields compared to plants with 2 or 3 stems per plant. The yields of fruits in class >200 g in plants with 4 stems was also lower compared to the weight yield of plants with 2 and 3 stems per plant. No significant differences in terms of weight yields of fruits in class >200 g were found between plants with 2 stems and with 3 stems per plant. In terms of media container, the plants grown on polybag tended to have a higher total yields and yield of fruits in class >200 g compared to yields of plants grown on slab, however, the differences were not significant. Production of sweet pepper using 3 stems per plant and polybag container could be recommended as alternatives in growing sweet pepper.
Van Doorn J.,Applied Plant Research |
Vreeburg P.J.M.,Applied Plant Research |
Van Leeuwen P.J.,Applied Plant Research |
Dees R.H.L.,Applied Plant Research
Acta Horticulturae | Year: 2011
Soft rot is causing increasing damage in the flower bulb industry. Bulbous ornamentals such as Hyacinthus, Dahlia, Iris, Muscari, Freesia and Zantedeschia can be infected. Soft rot in flower bulbs is mainly caused by Dickeya spp. (Dickeya spp.) and Erwinia carotovora subsp. carotovora (Pectobacterium carotovorum spp. carotovorum).To identify and detect these soft rot bacterial species in several bulbous ornamentals, standard PCR methods were used. During the last four years, research was directed to optimalize cultural practises in especially Hyacinthus to avoid or minimize bacterial soft rot. To evaluate the incidence and infection route of Erwinia spp. in the production chain of hyacinth bulbs, field plots were infected by planting diseased hyacinth, iris and Zantedeschia bulbs. Subsequently, crop rotation with different flower bulb species was applied on these field plots during two growing seasons. Harvested bulbs were analysed during the handling and storage of the bulbs for Erwinia spp. by assessing symptoms as well as by using bacterial culturing- and PCR techniques. The survival of Erwinia in water and on materials, used in flower bulb handling, was studied. Results concerning the optimalization of bulb handling during the production chain to avoid or to minimize the incidence of bulb soft rot are also presented.
Runia W.T.,Applied Plant Research
Communications in agricultural and applied biological sciences | Year: 2012
With increasing worldwide restrictions for soil fumigants, growers loose an important tool to control soilborne pests and pathogens. Environmentally friendly alternatives are urgently needed and anaerobic soil disinfestation (ASD) may be one of them. Traditional ASD with fresh grass is already applied in open field vegetables but the mode of action is unknown. Therefore, trials were performed under controlled conditions using soil-filled buckets, in which several processed defined organic materials were incorporated and compared with fresh grass. The effect of inundation was also studied. Target organisms were Pratylenchus penetrans, Meloidogyne hapla, Globodera pallida and Verticillium dahliae. Results showed that grass (traditional ASD) was less effective than the organic materials. All materials proved to be effective at 16 degrees C against all target organisms. However, exposure time, dosages, soil type and the temperature at which the experiments were performed influenced the effectiveness. P. penetrans was eliminated most easily whereas V. dahliae was most difficult to control. Efficacy was higher in sandy soil than in light marine clay. Inundation at 16 degrees C proved to be effective against P. penetrans and G. pallida in both soil types at sufficient exposure times. A soil temperature of 8 degrees C was sometimes too low for efficacy. Gas production of CO2, NH3, H2S, CH4 and N2O and gas consumption of O2 and production of fatty acids during ASD proved to depend on type of organic materials, soil type, temperature, dosage and exposure time. This first step in unravelling the mode of action has already shown several critical parameters for efficacy. Additional knowledge about the complete mechanisms of action may lead to a more reliable, effective and quicker soil disinfestation.
Evenhuis B.,Applied Plant Research |
Nijhuis E.,Plant Research International |
Lamers J.,Applied Plant Research |
Verhoeven J.,Applied Plant Research |
Postma J.,Plant Research International
Acta Horticulturae | Year: 2014
Phytophthora cactorum is an important threat in strawberry propagation and production. No reliable non-chemical control measures are available. Therefore different control strategies were tested. Spread of pathogen infection can be reduced by disinfection of the irrigation water. Slow sand filtration effectively removed P. cactorum from drain water, i.e., disease severity in strawberry plants was reduced with 45 to 65% and rhododendron baits showed a 95-100% reduction of P. cactorum after the drain water had passed the sand filter. However, upstream movement of P. cactorum was detected within the unit. A complementary strategy to reduce the damage caused by P. cactorum is to enhance disease suppressive properties of the soilless substrate. Pasteurization of the substrate mixtures showed increased levels of disease, indicating that biological factors might play a role in disease suppression. Antagonistic bacteria inhibiting growth of P. cactorum were present in roots, rhizosphere as well as in the crown. However, compost amendment or other additions did not elevate suppressiveness. Further experiments were performed where different beneficial microorganisms and/or elicitors were added. The most promising treatments were salicylic acid, followed by inoculation with the endophytic fungus Acremonium strictum and growing Lepidium sativum previous to the crop.
Runia W.T.,Applied Plant Research |
Molendijk L.P.G.,Applied Plant Research |
Van Den Berg W.,Applied Plant Research |
Stevens L.H.,Plant Research International |
And 2 more authors.
Acta Horticulturae | Year: 2014
Seed potato production is threatened by potato cyst nematodes (PCN). Seed potatoes can only be grown on PCN-free declared potato fields. A seed potato grower chose inundation, flooding his soil, for controlling PCN because resistant cultivars are economically less advantageous and catch crops or granular fumigants gave insufficient results. Inundation is widely used in bulb cultures in The Netherlands to control parasitic nematodes and selectively also pathogenic fungi. Research was performed on the efficiency of inundation against PCN species Globodera pallida and the causal fungal agent of potato wilt Verticillium dahliae (Vd) in a 30 ha field. The effect on soil fertility and texture was also studied. A technical manual for large-scale inundation was written for growers and economic evaluation was performed. Results showed that after 16 weeks of inundation 99.9% of the contents of artificially applied G. pallida cysts was eliminated. Vitality of V. dahliae was reduced with 84%. Incorporation of B. juncea did not increase efficiency. Anaerobic soil disinfestation (ASD) with incorporated B. juncea in the dike surrounding the field, showed a lower efficiency against G. pallida due to incorrect application. Naturally occurring beet cysts lost their vitality after inundation. Incorporation of B. juncea increased soil suppressiveness against Rhizoctonia solani whereas inundation leveled out this effect. By slow release of water after inundation soil texture remained unchanged. Changes in fertilizer content were affected both by the growth and incorporation of B. juncea and by inundation. An increase of sodium and of the electrical conductivity (EC) was noticed. Inundation proved to be highly effective in controlling PCN and Vd and economically feasible for practical application. Long-term effects have to be monitored and effects on other soil quality aspects, both biological, chemical and physical should be taken into account in future research. For some regions in The Netherlands inundation is a new tool for seed potato growers in their Nematode Control Strategy.